Evaluating tissue characteristics including identification of injured tissue or alteration of the ratios of native tissue components such as shifting the amounts of normal myocytes and fibrotic tissue in the heart, identifying increases in the amount of extracellular components or fluid (like edema or extracellular matrix proteins), or detecting infiltration of tumor cells or mediators of inflammation into the tissue of interest in a patient, such as a human being, is provided by obtaining a first image of tissue including a region of interest from a first acquisition, for example, after administration of a contrast agent to the patient, and obtaining a second image of the tissue including the region of interest during a second, subsequent acquisition, for example, after administration of a contrast agent to the patient. The subsequent acquisition may be obtained after a period of time to determine if injury has occurred during that period of time. The region of interest may include heart, blood, muscle, brain, nerve, skeletal, skeletal muscle, liver, kidney, lung, pancreas, endocrine, gastrointestinal and/or genitourinary tissue. A global characteristic of the region of interest of the first image and of the second image is determined to allow a comparison of the global characteristic of the first image and the second image to determine a potential for a change in global tissue characteristics. Such a comparison may include comparison of mean, average characteristics, histogram shape, such as skew and kurtosis, or distribution of intensities within the histogram.